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Varicella & Pregnancy

April 29, 2018
Sam Ashoo

Treatment in pregnancy:

Chicken Pox Infection
  • Immunized or Hx of past infection:
    • exposure: nothing to do.
    • simple rash: acyclovir 800mg PO 5x/day for 7 days
    • severe infection or pneumonia, admit for IV acyclovir and supportive care.
  • Not Immunized:
    • exposure: consider VZIG, give first dose within 96 hours if possible, and up to 10 days from exposure.
    • simple rash: acyclovir 800mg PO 5x/day for 7 days
    • severe infection or pneumonia, admit for IV acyclovir and supportive care.
Zoster (Shingles)
  • acyclovir 800mg PO 5x/day for 7 days 
Note:
  • No role for VZIG if patient is immunized or has Hx of prior infection.
  • VariZIG not proven to help once infection occurs, only in reducing chance of developing infection.
  • Women should be immunized as soon as possible, preferably 1 month prior to becoming pregnant, or as soon as possible after delivery.
  • VariZIG is given to pregnant non-immunized women who are exposed (legit exposure) with plans for vaccination after delivery.
  • Acyclovir is given to anyone who is vaccinated and shows symptoms.

Background: 

  • Chickenpox is caused by the varicella-zoster virus, a member of the herpes family of viruses.
  • Most people are exposed or immunized as children.
  • Infection is less severe in children than adults and usually has less morbidity.
  • The vaccine was introduced in 1995.
  • Acute infections causes a rash of the fact-trunk- and extremities that causes macule-papule-then vesicles then crusting. Lesions appear over 4 days, crust by day 6 and slough off within a week or two.
  • Prodrome includes fever, malaise, and myalgia one to four days prior to the onset of rash.
  • Vaccination protects 98-99% of people after 2 doses.
  • Those with varicella can pass it along more easily than those with zoster.
  • People are infectious from 1-2 days prior to symptoms until all lesions have crusted over.
  • Passage also occurs from exposure to secretions from mucus membranes in varicella, more so than with exposure to fluid in vesicles.
  • Incubation is 10-21 days post exposure.

Epidemiology:

<2% of infections occur in adults >20 yo, about 25% of mortality is in this age group.  1 to 5 cases per 10,000 is the estimated incidence, but it isn’t reportable so exact numbers are unknown.

Complicatons: 

Complications are more common in adults than children and include
  • meningitis, encephalitis, cerebellar ataxia, pneumonia, glomerulonephritis, myocarditis, ocular disease, adrenal insufficiency, and death.
  • Secondary bacterial infections can also occur in patients with significant cutaneous disease.
 Mother:
  • Maternal varicella during pregnancy is associated with the development of herpes zoster during infancy.
  • Varicella infection  immediately before or after delivery puts the baby at risk for neonatal varicella, which varies from mild rash to disseminated infection.
  • Maternal zoster is generally not associated with fetal or newborn disease.
  • Most common complication of varicella in pregnancy is pneumonia.
    • There is an increased rate with varicella in pregnancy but the numbers have improved with antiviral therapy. It was reported as up to 20% experiencing pneumonia, but may be as low as 2.5% of cases now. Smoking and having >100 vesicles increases the risk.
    • The pneumonia usually develops within one week of the rash
    • The clinical course is unpredictable and may rapidly progress to hypoxia and respiratory failure.
    • CXR findings include a diffuse or miliary/nodular infiltrative pattern
Fetus:
  • Congenital Varicella Syndrome occurs in less than 2% of pregnancies where mom has primary varicella in the first 20 weeks.
  • It is more rare after 20 weeks gestation.
  • Only one published case report of this occurring due to zoster since 1987
  • Congenital varicella syndrome includes limb hypoplasia, skin lesions, neurologic abnormalities, and structural eye damage.
  • Mortality rate of 30 percent in the first few months of life.
  • 15 percent risk of developing herpes zoster by age 4.

References:

  1. Cytomegalovirus, parvovirus B19, varicella zoster, and toxoplasmosis in pregnancy. Practice Bulletin No. 151. American College of Obstetricians and Gynecologists. Obstet Gynecol 2015;125:1510–25.
  2. CDC, Prevention of Varicella: Recommendations of the Advisory Committee on Immunization Practices (ACIP)  Direct Link
  3. Royal College of Obstetricians and Gynecologists, Chicken Pox In Pregnancy, Green-top Guideline No. 13, January 2015  Direct Download
  4. Enders G, Miller E, Cradock-watson J, Bolley I, Ridehalgh M. Consequences of varicella and herpes zoster in pregnancy: prospective study of 1739 cases. Lancet. 1994;343(8912):1548-51. PubMed
  5. Stone KM, Reiff-eldridge R, White AD, et al. Pregnancy outcomes following systemic prenatal acyclovir exposure: Conclusions from the international acyclovir pregnancy registry, 1984-1999. Birth Defects Res Part A Clin Mol Teratol. 2004;70(4):201-7.PubMed
  6. Cohen A, Moschopoulos P, Stiehm RE, Koren G. Congenital varicella syndrome: the evidence for secondary prevention with varicella-zoster immune globulin. CMAJ : Canadian Medical Association Journal. 2011;183(2):204-208. doi:10.1503/cmaj.100615. PubMed

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